The present invention relates to propellers, and particularly to a device for measuring the pitch and rake of a propeller. More particularly, the present invention relates to a pitch and rake gauge capable of pivotable movement about an axis, the pivotable movement being measured with digital accuracy.
In the disciplines of manufacturing and repairing propellers used in boats, planes, and the like, it is desirable to determine with some degree of accuracy the pitch and rake at numerous points on the propeller blades. As used herein, xe2x80x9cpitchxe2x80x9d relates to the theoretical distance a propeller would advance longitudinally (due to the slope of the blade) in one revolution of the propeller. xe2x80x9cRake,xe2x80x9d as used herein, relates to the inclination of the blade surface from the perpendicular.
According to the disclosure, a pitch and rake gauge measures the pitch and rake of a blade on a propeller. The gauge comprises a propeller mount configured to support a propeller thereon. A measurer is coupled to the propeller mount and adapted to engage the blade in a stationary position. A rotational sensor gauges rotational movement of the measurer and provides signals representative of the gauged rotational movement. A display receives the signals and provides an output based on the signals.
In the disclosed embodiment, the rotational sensor is coupled to the propeller mount and is adapted to move between a pitch-sensing mode and a rake-sensing mode. The rotational sensor is illustratively an optical encoder. The rake sensor includes a straight-edge configured to extend along a radial line relative to the blade of the propeller. The pitch sensor includes two feet in spaced-apart relation, the two feet being configured to contact the propeller blade at two points substantially equally distant from the axis of the propeller.
The gauge illustratively includes an arm extending radially outwardly from the propeller mount, and a support member attached to the arm. The pitch and rake sensors are rotatably mounted upon the support member.
The disclosure also contemplates a method of measuring a characteristic of a blade on a propeller having an axis. The method includes the steps of positioning the propeller on a propeller mount, connecting a measurer to the propeller mount, assigning a neutral position for the measurer from which rotational measurements will be based, and moving the measurer into contact with a selected position on the propeller blade while rotating the measurer as necessary. The rotation of the measurer relative to the neutral position is then determined, and an electronic indication of the rotation of the measurer relative to the neutral position is provided.
According to the disclosure, the neutral position-assigning step includes zeroing the measurer by placing it in contact with a calibrating platen. A pivot member carries the rake sensor and the pitch sensor, the pivot member presenting one of either the rake sensor and pitch sensor to the propeller blade in order to determine either the rake or the pitch of the blade.
Additional features of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived.